The Japanese government is reportedly planning to take retaliatory steps against the United States as Washington has declined to exempt Tokyo from heavy duties on steel and aluminum imports.

Japan's public broadcaster NHK said on Thursday that the country was considering slapping tariffs on US exports worth 409 million dollars in retaliation for steel and aluminum import tariffs imposed by President Donald Trump in March allegedly on national security grounds.

Based on international trade rules, the government will notify the World Trade Organization (WTO) of the plan before the end of this week, according to the NHK.

The broadcaster also announced that Japan's planned retaliatory tariffs on US exports would be equal in value to the duties levied by Washington.

US President Donald Trump signs Section 232 Proclamations on Steel and Aluminum Imports in the Oval Office of the White House, in Washington, DC, March 8, 2018. (Photo by AFP)

But a Japanese government official told Reuters that while Tokyo had been considering retaliatory steps against the US based on WTO rules, no final decision had so far been made on the issue.

"Nothing has been decided on what specific response we should take. We're scrutinizing the impact of US tariffs on Japanese companies, and calling for Washington to offer Japan an exemption," the official said on condition of anonymity.

On March 8, the US president imposed a 25-percent tariff on steel imports and a 10-percent tariff on aluminum imports.Washington later granted temporary exemptions from those tariffs to several US allies but not Japan, which came as a shock given Japanese Prime Minister Shinzo Abe's close ties with Trump.

Tokyo has so far been wary of following in the footsteps of China and the European Union, which have responded to the US decision on tariffs with reciprocal threats.

Abe, meanwhile, is in a precarious situation, facing decreasing approval ratings at home - which could further go down if he is seen as too soft on trade with the US - while having to avoid upsetting America as its main ally.

Comment: While Trump may be attempting to do what's best for the US, it no longer holds the influence on global trade that it once did and many countries are pushing back: